土壤非饱和带柴油迁移的模拟实验

Simulated experiment on transport of diesel oil in unsaturated soil zone

通过土柱模拟实验研究了0#柴油及其饱和水溶液在不同含水率的砂土及壤土中的入渗迁移及残留特征.结果表明,柴油在壤土中的入渗速率小于砂土,且随含水率的增加逐渐减小,而柴油在砂土中的入渗速率则随含水率的增加先增大后减小.入渗结束后,相同深度的土柱中柴油残留量随含水率的增加明显降低,沿土层深度呈先增后降的弓形趋势.随着再分布时间的延长,砂土柱中柴油残留量随土层深度逐渐增大,壤土柱中柴油含量变化较小.柴油饱和水溶液在壤土中的入渗速率明显小于砂土,穿透曲线的峰值滞后于砂土,入渗过程中,壤土中渗出液的柴油浓度小于砂土.入渗结束后,深度小于10 cm的壤土柱中集中了绝大部分柴油,而砂土中柴油残留量则略低于壤土.

Soil column simulation tests were carried out to study the infiltration and residues characteristics of 0#diesel（ dissolved and light non-aqueous phase liquids,LNAPLs） in loamy and sandy soils with various moisture content. It was found that the wetting front advancing rate of diesel oil in loamy soil decreased with the increase of moisture content,and the rate was slower than in sandy soil. In sandy soil columns,the wetting front advancing rate of diesel oil first increased then decreased with the increase of moisture content. The infiltration experiment also showed that the residue of diesel oil presented an overall decline with the increase of moisture content in unsaturated zone,and the maximum residue was located at the middle of the soil column. The amount of residual diesel oil increased in sandy soil along the depth of columns after redistribution,while the oil content changed little in loamy soil. The velocity of dissolved diesel oil seeping in sandy soil proved much faster than in loamy soil. The peak of break-through curves of loamy soil lagged behind as compared to those of sandy soil. Concentrations of the exudates from soil columns with loamy soil were lower than that with sandy soil. The residue of diesel oil congregated in a range of 0—10 cm depth in loamy soils,which was higher than that in sandy soil.